# 计算圆的面积
# 给一个半径R； 计算面积并且返回

import math


def compute_area_of_circle(r):
    """
    :param r: 半径R
    :return: area_of_circle
    """
    return round(math.pi * r * r, 2)

print(f"area of 2 is :{compute_area_of_circle(2)}")
print(f"area of 3.14 is :{compute_area_of_circle(3.14)}")
print(f"area of 6.78 is :{compute_area_of_circle(6.78)}")